As understood in the art, a cognitive radio is a communication device that is capable of wireless communication in a network, and is also able to change its communication parameters to adapt to a changing communication environment. Notice of Proposed Rulemaking and Order Federal Communications Commission (FCC) 03-322 explains the concept of interruptible spectrum leasing. This type of operation allows for licensing that can be suspended when the spectrum is needed for some urgent reason, such as, for example, emergency operations. The FCC also expects that cognitive radio technologies can identify spectrum that is available for leased use and ensure that the spectrum reverts to the license under predetermined conditions.
One of the techniques for accomplishing access/reversion is to employ handshaking. This technique expects the radio systems to be compatible, that is, able to communicate with each other. Another technique permits a secondary licensee device to operate only if the secondary licensee can verify by handshaking that the device can operate on the frequency. A further technique requires the secondary licensee to cease operations when the secondary licensee receives signaling information from the primary licensee system to stop operating. In a beacon system, as known in the art, the secondary licensee receives a beacon indicating that operations are allowed.
The methods described by FCC 03-322 are critical for suspending secondary licensee operation when spectrum is required for important use. Further, other conditions exist where cognitive radio technologies may be useful, such as when it is desirable to modify the transmission method depending on interference.
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